therealbarenziah / toying-with-v8

Toying with v8 engine

Toying with v8

Reminder

There are four main stages that code inside V8 passes through :

• JavaScript Code - this is what you wrote
• Hydrogen - intermediate code representation where optimizations are applied
• Lithium - machine specific code used to generate native code
• Machine Code - this is what the computer understands

Resources

• Awesome Medium article about it (the quote above is from it)
• jsvu : README is well documented
• Learn about v8 ByteCode (picture related)

Setup

• Follow the Medium article
• Instead of manually compile the engine, use jsvu
• Do NOT select "QuickJS" engine, it's integration is currently broken (7 January 2020)
• I only selected v8-debug (non-debug version doesn't seem to support --print-bytecode and some fun stuff like this)
• Assuming you dutifully followed the jsvu README, you've updated your $PATH already. Now you can just:
• v8-debug --print-bytecode myFile.js
• It will display in standard output (console): from there you can cat (concatenate) into a file or whatever

Available flags

• Gist (may be outdated)
• $ v8-debug --help (won't be outdated)

Todo

• User-friendly way to display the aforementioned steps (some frontend)